Double jaw for a knife switch



May 7, 1968 E. w. MOODIE ET AL DOUBLE JAW FOR A KNIFE SWITCH 5 Sheets-Sheet 1 Filed March 30, 1967 INVENTORS ERNEST W MOOD/E WILL/AM C CARLYLE yaw/,4. W

May 7, 1968 E. w. MOODIE ET AL 3,382,340

DOUBLE JAW FOR A KNIFE SWITCH Filed March 50, 1967 5 Sheets-Sheet 2 INVENTORS ERNEST W. MOOD/E WILLIAM C. CARLYLE /M M E. W. MOODIE ET AL DOUBLE JAW FOR A KNIFE SWITCH May 7, 1968 Filed March 50, 1967 5 Sheets-Sheet 5' ""Hm. Q

. INVENTORS ERNEST W. MOOD/E W/LL/AM C. CARLYLE M y. W

United States Patent 3,382,340 DOUBLE JAW FOR A KNIFE SWITCH Ernest W. Moodie, Downsview, Ontario, and William C. Carlyle, Toronto, Ontario, Canada, assignors to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Mar. 30, 1967, Ser. No. 627,065 Claims priority, application Canada, Sept. 24, 1966, 971,217 6 Claims. (Cl. 200-166) ABSTRACT OF THE DISCLOSURE A pair of outer jaw members with U-shaped upper portions have inwardly turned lower flanges supported respectively on outwardly turned flanges of a pair of inner jaw members having upstanding contact portions disposed between facing sides of the U-shaped upper portions of the outer jaw members.

This invention relates to electric switches of the knifeblade type, and more particularly to a knife-blade switch having an improved double jaw for receiving a pair of spaced contact blades and to a method of constructing the double jaw.

Ordinarily each conductive path through a knife switch includes a single contact blade receivable in a cooperating single contact jaw. To increase the current carrying capacity of the switch, the cross-section of the single blade can be increased and the size of the cooperating jaw can be correspondingly increased. Alternatively, the increased capacity can be obtained by securing two of the blades together in spaced-apart relationship and providing a double jaw that will receive the two blades.

An object of the present invention is to provide an improved double jaw for a knife switch which can be formed from parts derived from parts of a single jaw.

Another object is to provide an improved method of constructing a double jaw of a knife switch by using modified parts of a single jaw.

Other objects and advantages of this invention will be readily apparent from the following specification wherein reference is made to the drawings, in which:

FIG. 1 is a top plan view of a knife switch in accord ance with this invention;

FIG. 2 is a side elevation of the switch of FIG. 1;

FIG. 3 is a front elevation of the double jaw of the switch of FIGS. 1 and 2;

FIG. 4 is an exploded perspective view of the double jaw of FIG. 3;

FIGS. 5 and 6 are sectional views taken generally along the lines 55 and 6-6, respectively, of FIG. 3;

FIG. 7 is a side elevation of a part of the double jaw of FIG. 3; and

FIG. 8 is a front elevation of parts of the double jaw of FIG. 3 Showing their derivation from a Single aw.

A complete double-bladed knife switch is shown in FIGS. 1 and 2 with a double jaw 10 constructed in accordance with the present invention shown as receiving a pair of parallel-spaced switch blades 11a and 11b. A partially open position of the blades 11a and 11b is indicated by broken lines in FIG. 2. The double jaw 10 is mounted on an electrically conductive plate 12 to which are attached a pair of conventional terminal connectors 14. The plate 12 in turn is mounted on an insulating base 15.

Each of the blades 11a and 11b has a beveled entry edge 16 and both are pivotally attached to a conductive plate 17 by mean-s of a pair of spaced pivot brackets 18a and 18b mounted upon the plate 17 and a pivot bolt 19 extending between the pivot brackets. The conductive plate 17 is mounted on an insulating base 21 and has attached thereto a pair of conventional terminal connectors 22.

The blades 11a and 11b are maintained in parallelspaced relationship by a conductive spacer 23 of rectangular configuration positioned between the blades at their approximate longitudinal centers and by a pair of conductive washers 24 disposed between the blades around the pivot bolt 19. The spacer 23 is attached to the blades 11a and 11b by a plurality of rivets 25 which also serve to secure a pair of insulating brackets 26 to the outside surfaces of the respective blades. It will be noted that the blades 11a and 11b are connected electrically in parallel by the spacer 23, the washers 24, the pivot bolt 19 and the pivot brackets 18a and lSb.

Referring now to FIGS. 3 and 4, the improved double jaw 10 of this invention comprises a stationary inner jaw assembly 30, a pair of outer jaw members 32a and 32b, a pair of spring members 33a and 33b, and a suitable fastening means shown as comprising a pair of nut plates 34a and 34b and a pair of cooperating bolts 35.

The inner jaw assembly 30 comprises a pair of identical, generally L-shaped, inner jaw members 40a and 4%, preferably made of copper or a copper alloy. Each of the jaw members 40a and 40b has a contact leg portion 42 parallel with the operating plane of the blades 11a and 11b, and an angled mounting foot portion 43 provided with a short upturned flange 44 remote from the contact leg portion. The members 40a and 40b are fastened together in back-to-back relationship preferably by a pair of rivets 45 received in respective pairs of aligned counter-bored holes 46 in the contact leg portions 42. The counter bores of the holes 46 receive the heads of the respective rivets 45 so that the rivet-s do not extend beyond the exposed outer contacting surfaces of the leg portions 42. The pair of leg portions 42 thus define a rigid center contact piece of the inner jaw assembly 30. The top or outer end faces of the leg portions 42 have respective outwardly facing bevels 49 which together define a blunted wedge configuration at the area of entry of the blades 11a and 11b.

The outer jaw members 32a and 32b are preferably made of an electrical conductive material such as copper or copper alloy and each has a U-shaped bend at its upper portion defining an inner depending contact arm 48 spaced from an outer connecting leg portion 49. Each leg portion 49, has, perpendicular to its lower portion, an inwardly-turned mounting foot 50.

Each of the springs 33a and 33b has a foot portion supported on one of the mounting feet 50 and an upwardly-extending biasing portion engaging its associated one of the contact arms 48 so as to bias the contact arms inwardly toward the center contact piece.

As shown in FIG. 6, each of the mounting feet 50 of the respective outer jaw members 32a and 32b has a slotted opening 51. As shown in FIG. 5, each of the springs 33a and 33b has a slotted opening 52. The slotted openings 51 and 52 accommodate the jaw fastening bolts 35.

In FIG. 8, the outer jaw members 32a and 3212 are arranged to show how they can be formed from the two halves of a conventional single jaw 53 by a saw cut indicated by the shaded area 55. A conventional central cylindrical hole in the bottom portion of the single jaw then becomes a half-round open-ended slot in each of the two halves. Each of the slots thus formed is elongated to form the slots 51 by machining to the proportions indicated in FIG. 6. Alternatively, the central cylindrical hole may be elongated before the sawing operation.

Similarly, the springs 33a and 33b can be formed from a conventional single jaw spring by a saw cut indicated by the shaded area in FIG. 8, by cutting through a similar central cylindrical hole to define half-round slots which are thereafter elongated to form the slots 52 shown in FIG. 5. Alternatively, the cylindrical hole may be elongated before the sawing operation.

As shown in FIGS. 4, 7, and 8, the outer jaw members 32a and 321) each have a triangular inwardly-turned portion 58. As shown in FIG. 2, the inwardly-turned portions 53 prevent contact between portions of the blades 11a and 11b immediately adjacent the beveled edges 16 and the respective jaw members 32a and 3211 when the blades are in the closed position.

As shown in FIGS. 3 and 6, the upturned flanges 44 of the feet of the inner jaw assembly 30, together with the bolts 35, positively locate the outer jaw members 32a and 32b with respect to the inner jaw assembly despite the openings 51 being slotted. Similarly, as shown in FIGS. 3 and 5, the springs 33a and 3312 are then positively located by the bolts and the inner surfaces of the respective leg portions 49 of the outer jaw members 32a and 32b despite the openings 52 being slotted.

The bolts 35 in combination with the nut plates 34a and 34b secure the outer jaw members 32a and 32b, the springs 33a and 33b, and the inner jaw assembly 30 together and to the conducting plate 12. Thus the bolts 35 and nut plates 34a and 34b together with the upturned flanges 44 positively maintain the parts of the double jaw 10 in proper position.

Referring to FIG. 2, operation of the double knife switch to complete a conductive path between the pairs of terminal connectors 14 and 22 requires rotating the blades 11a and 11b about the pivot bolt 19 by means of the insulative brackets 26 from a position indicated by the broken lines in FIG. 2 counterclockwise into initial engagement with the jaw assembly 10 and then forcing the blades into the closed position shown. As the blades 11a and 11b make initial contact with the jaw assembly 30, each of the blades 11a and 11b wedges between the center contact piece of the inner jaw assembly 30 and the respective one of the outer jaw members 32a and 32b forcing outwardly the conducting leg portions 49 of the respective outer jaw members 32a and 32b against the restoring force of the respective springs 33a and 33b. The restoring force of the springs 33a and 33!) together with the resilience of the outer jaw members 32a and 32b maintain snug contact between blades 11a and 11b and the jaw 10. Substantially balanced and opposite forces on both contact leg portions 42 aid in maintaining the center contact piece of the inner jaw assembly stationary.

We claim:

1. A double jaw for a knife switch having a pair of parallel-spaced pivoted blades, said jaw comprising an inner jaw assembly, a pair of outer jaw members, a pair of springs, and fastening means, said inner jaw assembly comprising a pair of substantially identical L-shaped inner jaw members fastened intimately back-to-back defining a rigid center contact piece for contact with an inner side of each blade and having a pair of mounting feet extending outwardly in opposite directions from the center contact piece, each of said outer jaw members having a curved portion interconnecting an inner depending contact arm portion and an outer connecting leg portion and having a mounting foot portion extending inwardly toward the center contact piece substantially at a right angle with respect to the connecting portion leg, said mounting foot portions being juxtaposed on the respective mounting feet of the inner jaw assembly, said springs having portions juxtaposed on the respective mounting foot portions of the outer jaw members and portions bearing against said inner arm portions, respectively, thereby biasing said inner arm portion toward the stationary center piece, and said fastening means fastening the springs, the respective mounting feet of the outer jaw members, and the respective mounting feet of the inner jaw assembly together in said juxtaposed relations.

2. A jaw as claimed in claim 1 characterized in that the inner jaw members are fastened back-to-back with a rivet received in aligned openings counter-bored to receive the respective heads of the rivet.

3. A jaw as claimed in claim 1 wherein each mounting foot of the inner jaw assembly is provided with a short upturned flange portion remote from and parallel to said center contact piece for constraining the associated outer jaw member in fixed position.

4. A jaw as claimed in claim 1 wherein the mounting feet of the outer jaws have slotted openings for fastening to the mounting feet of the inner jaws.

5. A knife switch having an improved double jaw electrically connected to a terminal means by a conducting means and receiving a pair of parallel spaced-apart blades, said double jaw comprising an inner jaw assembly having a stationary center contact piece for electrical contact with an inner side of each blade and having a pair of mounting feet extending oppositely from said center contact piece, a pair of short upturned flange portions respective to each mounting foot remote from and parallel to the center contact piece, a pair of separate outer jaws respectively constrained in fixed position with regard to the inner jaw assembly by the pair of upturned flange portions to provide contact with an outer side of each of the blades, a pair of springs, the springs being positioned to maintain tight contact between the outer jaws and the blades, and fastening means fastening together the outer jaws, the springs, the inner jaw assembly, and said conducting means.

6. A knife switch having an improved double jaw electrically connected to a terminal means by a conducting means and receiving a pair of parallel spaced apart blades, said double jaw comprising an inner jaw assembly having a stationary center contact piece for electrical contact with an inner side of each blade and having a pair of mounting feet extending oppositely from said center contact piece, a pair of separate outer jaws each for contact with an outer side of one of the blades, each of said outer jaws having a mounting foot portion extending inwardly toward the center contact piece, said mounting foot portions being in juxtaposed relation respectively with the mounting feet of the inner jaw assembly, an opening in each mounting foot portion aligned with an opening in the one of the mounting feet with which it is juxtaposed, a pair of springs each positioned to maintain tight contact between the outer jaws and the blades, and fastening means received in the aligned openings fastening together the outer jaws, the springs, the inner jaw assembly, and said conducting means.

References Cited UNITED STATES PATENTS 2,256,734 9/1941 Cornell et al 200166 2,765,380 10/1956 Graybill 200170 3,118,990 1/1964 Jansson 200166 ROBERT K. SCI-IAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner. 

